Propeller



May 20, 1924. 1,494,964

1 H. M STOLLER PROPELLER Filed May 17. 1919 2 //1 van for:

Hug/2 /V., $f0//e/.'

Patented. May 20, 1924.

umrao s ArEs PATENT OFFICE.

HUGE KLSTOLLEB, OF NEW YORK, N. Y., ASSIGNOB TO WESTERN ELECTBTCCOMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PROPELLEB.

Application filed Kay 17,

To all whom it may concern:

Be it known that I, HUGH M. S'ropLnR, a citizen of the United States ofAmerica, re-

siding at New York in the county of New York, State of New'York, haveinvented certain new and useful Improvements in Propellers, of which thefollowing is a full, clear, concise, andexact description.

This invention relates to pro ellers and has particular reference to auid driven propeller which may be used to drive small electricalgenerators, or other similar pieces of apparatus.

Its object is the provision of a propeller in which, when. its speed ofrotation exceeds a certain amount, an automatic and proportional changeof the pitch, of the blades will be caused, and thereby restrictvariations in its own speed under variations in the velocity of thedriving fluid. The speed of operation of the apparatus towhich it isattached will thus be more regular than otherwise would be the case.

The invention comprises a propeller having any suitable number of arms,the general surfaces of which are inclined, as usual, both with respectto the longitudinal and trans: verse axes of the hub. The rear portionof each arm ,is relatively flexible and is at tached to the main body ofthe arm and clined rearwardly with respect to the vertical plane and thedirection of rotation. When the driving fluid impinges upon the surfaceof the propeller arm it rotates, and this rotation results in thegeneration of considerable centrifugal force in the various parts of thearm. The centrifugal force generated in the flexible surface abovementioned, tends, due to the inclination of said surface, to bend thesurface toward the vertical plane which would be in a direction tendingto increase the pitch of the arm and check its speed, and therebyprevent a rise in the speed of rotation of the ropeller. In a referredform of the propeller, this flexib e portion is made of sheet metalhavin considerable mass, so that the centrifuge force flgenerated .issuflicient to produce quite a de ection of the surface, and thereby moreeffectively control the speed of the propeller.

' This invention will be better understood by reference to the followingdetailed description taken in connection with the acccmpanying drawing,in which Fig. 1, rep- 1819. Serial N0. 297,752.

ance with this invention, Fig. 2 represents.

a side view of the same in which the position of the propeller for highwind velocities is shown in dotted lines, and Fig. 3 represents a topview of the propeller.

The invention is illustrated in Fig. 1 which is a perspective view ofthe device. As shown, the generator, or other apparatus to be driven, 1,is connected by a shaft 2 to a propeller having a hub 3 and arms 4 and5. A greater number of arms can, of course, be provided if desired. Froman inspection of the figure, the arms will be seen to be inclined withrespect to the longitudinal axis of the hub 3, the direction of rotationof the propeller being indicated by an arrow. In accordance with thisdirection, the edges 6 and 7, respectively, are the forward ed es of thearms, 4 and 5, and are formed y bending the metal of the arms back onitself and riveting the line of the overlapping portion as shown, andedges 8 and 9 are the rear edges of the arms a and 5. It will thus beseen that the front portions 6 and 7 of each blade are very rigid andformed of two layers of metal and the rear portion 10 is relativelyflexible being made of a single layer of material. The overlap isriveted along the edges by rivets 11 as shown.

The flexible ortion 10. is inclined as a whole. rearwar ly y from avertical plane .and with respect to the direction of rotation, and thuswill be considerably affected by the action of centrifugal force at highspeeds. Since this portion 10 is preferably formed of some materialhaving considerable mass, such as metal, when the propeller arms 4 and 5have attained a certain s eed of rotation, the centrifugal force of tese outer portions 12, corresponding to the well known law, F= willcause them to Fig. 2 illustrates a side view of the propeller of Fig. 1looking at the propeller will tend to assume due to centrifugal forcewhen the propeller is rotated at high speed.

\ It is apparent that this change in position of the portion 12 is dueto centrifugal force, since the center of mass of portion 12 in movinginto the plane shown in dotted lines, will move upwardly and rearwardlyso that consequently the center of mass assumes a position farther awayfrom the axis of rotation of the propeller. It will also be apparentfrom this figure, that when the propeller blade-tends to assume theposition shown in dotted lines that more of the driving wind will 'bespilled thereby tending to reduce the speed of rotation of thepropeller. i

Fig. 3 represents a top view of the pro peller of Fig. 1, and shows infull lines the position ofthe propeller blade at rest, while showing indotted lines its position for a high speed of rotation.

This invention is particularly applicable to wind driven generators usedon high speed vehicles, such as aeroplanes, which attain excessivelyhigh speed, a voltage regulation for the generators being provided bythe use of this invention.

What is claimed is: 1. A wind driven propeller, comprising a hub, apropeller arm on said hub, the forward portion of said arm with respectto the direction of the wind being rigid, the rear portion of said armcomprising flexible material so joined to the rigid portion that whensaid propeller arm is at rest the flexible portion is bent forwardly inthe direction of the wind and downwardly in the direction of the axis ofrotation and such'that for high speeds of rotation the center of mass ofthe flexible portion will be moved rearwardly and farther away from theaxis of rotation.

2, A wind driven propeller, comprising a hub, a metallic-propeller armon said hub, the forward part of said pro eller arm with respect to thedirection o the wind being of suflicient thickness to be rigid, the

thickened portion being of greater width near the hub than near theouter end of said arm, the rear portion of said propeller arm beingcomposed of metallic material sufiioiently thin to be flexible, therigid portion. and the flexible portion being so joined for thepropeller arm at rest that the flexible portion is bent forwardly in thedirection of the wind and downwardly in the direction of the axis ofrotation and such that for high speedspf rotation the center of mass ofthe flexible portion will be moved rearwardly and farther away from theaxis of rotation.

In witness whereof, I hereunto subscribe my name this 12th da of May A.D., 1919. HU- .H M. STOLLER.

